Hydroprocessing is taking place in a hydroprocessing catalytic reactor which is the key element of a hydroprocessing unit. Hydroprocessing catalytic reactors can have single or multiple catalyst beds. The number of catalyst beds within one reactor follows from the calculation of the maximum height of the bed, in the individual process and function. This is decided based on a number of constraints. These include catalyst activity and selectivity, catalyst lifetime, flow distribution considerations and safety.
The one or more catalyst beds in the reactor need to be supported to retain the catalyst but the support must enable process fluid to flow through the support to be processed In the reactor bed(s). Catalyst support grids in the reactor are built by a number of cassettes, each with a weight of 100-500 kg. As crane time often determines the time for assembly and disassembly of the catalyst support grid, the disassembly time is often in the range of 2 days, roughly the same as the assembly time. The catalyst support grid is covered by a screen for retaining the catalyst pellets. To enable through-flow of process fluid, the screen may be made of for example woven wire-mesh, flat printed pattern or welded wires and rods.
During operation, the functionality of the screen may be affected for example by coke deposition, by damaging during handling such as scaffolding on top of the screen, and occasionally by corrosion. When damaging occurs, the support grid needs to be dismantled, the affected cassette is brought to the workshop, where it is cleaned and repaired. Dismantling and reparation is cumbersome and time consuming. Some types of screens, e.g. some welded wires and rods screens may not be able to be repaired and the whole cassette needs to be replaced by a new.
US2012237415 discloses a modular catalyst bed support can be used to increase the number of catalyst beds available in a reactor. The modular catalyst bed support can include a lattice with a plurality of lattice openings and modules inserted into the lattice openings. The modular catalyst bed support can rest on top of an underlying catalyst bed, which can reduce or eliminate the need for attachment of the modular catalyst bed support to the walls of the reactor.
US2013064731 is directed to an upwardly convex fixed-bed catalyst support for a hydroprocessing reactor. The catalyst bed support includes an upwardly convex annular-shaped plate having an outer end in communication with the reactor inner surface, and an inner end in communication with a horizontal hub assembly.
U.S. Pat. No. 2,745,722 describes a reactor comprising a wall defining a reaction chamber containing a horizontally disposed bed of finely-divided catalyst, calking apparatus for depositing a supply of fresh catalyst about the peripheral edge of said catalyst bed in order to compensate for radial contraction thereof, said calking apparatus comprising a gas-tight seal in said wall above said catalyst bed, a rotatable conduit of comparatively small cross-sectional area entering said chamber through said seal and terminating in a discharge end at a point above and in proximity to the peripheral edge of said catalyst bed, and means connected to said conduit for maintaining said discharge end of said conduit above and in close proxitnity to said peripheral edge as said conduit is rotated.
U.S. Pat. No. 2,860,860 is describing a tray deck for a gas-liquid contact column. It comprises a number of parallel spaced beams extending across the column and supported at their ends by an annular flange secured, e.g. by welding, to the shell of the column and a plurality of deck sections which extend transversely between adjacent beams and which have along their transverse edges downwardly projecting stiffening flanges extending between the beams. The deck is completed by deck sections which rest partly on a beam and partly on the flange, the edges of the sections adjacent the shell being curved. The beams are secured to the flange by clamping members secured together by a bolt which may pass through a hole in the top flange of a beam or the upper flange may be notched to accommodate the stem of the bolt. The deck sections may be made of light gauge sheet metal, e.g. of stainless steel, nickel or “Monel” metal, (R.T.M.) and are of such sizes that a space is left between adjacent sections on the beams and between the sections and the shell of the column to allow for expansion. The sections have series of punched out slots with sharp or rounded corners to provide an aggregate slot area of between 7 and 50 per cent of the total tray area. The sections have centrally disposed reinforcements secured to their undersides and the transverse marginal edges of the sections are bent downwardly to form the stiffening flanges and may also have a tip turned inwardly from a flange under a reinforcement. The longitudinal edges of the sections extend beyond the flanges. The sections are of similar construction except that they have only one transverse stiffened edge and the reinforcements stop short of the curved edges of the sections. The sections are secured to the beams by bolts and washers, the washers being of such size as to overlie the marginal portions of adjacent sections and the seams of the bolts passing between the sections which are notched for this purpose if necessary. A section is provided in each tray deck to serve as a man-way and is secured by fasteners having removable nuts at both ends of a threaded bolt to a central portion of which is secured a plate adapted to lie between adjacent longitudinal edges and prevent rotation of the fastener.
US2012156111A discloses structure and method for adding a catalyst bed platform to an existing reactor without welding to the structural portion of the reactor walls. The structure is constructed from components that can be passed through an existing opening in a reactor. The structure allows a catalyst bed in an existing reactor to be divided into catalyst beds with a reduced length to diameter ratio.
U.S. Pat. No. 5,891,405A describes an exothermic heterogeneous catalytic synthesis reactor including at least one catalytic bed arranged in a cylindrical shell and provided with a bottom plate for containment of the catalyst, and at least one supporting shoulder for the bottom plate extending from the shell, includes a catalyst-seal support device including an annular element placed between the shoulder and the bottom plate. The annular element is fixed in a removable manner with the bottom plate and has a thermal expansion coefficient substantially equal to that of the shell.
EP0602288 discloses a moving catalyst bed reactor comprising a normally vertical cylindrical vessel provided at its upper end with a catalyst inlet and a reactant inlet and at its lower end with a catalyst outlet and an effluent outlet, and with a separation device arranged in the vessel near its lower end, the separation device comprises a downwardly tapering catalyst support having an outer edge which is joined to the wall of the vessel and a central opening which communicates directly with the catalyst outlet, the catalyst support is provided with perforations and with fluid withdrawal devices having screens preventing catalyst from passing which fluid withdrawal devices are arranged over the perforations and joined to the catalyst support.
In U.S. Pat. No. 6,878,351, a catalyst support structure e.g. for use in an ammonia oxidation reactor is disclosed, comprising a series of primary supports disposed above a catalyst bed, a lattice assembly disposed beneath the catalyst bed and on which the catalyst bed rests, said lattice assembly being suspended from the primary supports by suspending means extending through the catalyst bed. Preferably the support structure includes a static start-up burner arrangement in the form of one or more perforated tubes adjacent the primary supports.
In WO9110496, A catalytic reactor for gas phase reactions is disclosed. The reactor includes a housing, a porous catalyst support plate within the housing, a bed of catalyst particles within the housing and a fibrous filter pad extending across the housing to prevent transport of catalyst particles from the housing. The filter pad is resistant to clogging and imposes a low pressure drop across the reactor.
U.S. Pat. No. 5,527,512 discloses a light-weight and easily manufacturable catalyst support structure, which allows fluid flow into a catalyst bed in uniform distribution. The support structure, used for supporting a moving catalyst bed within a moving bed reactor having an upward flowing fluid phase, is formed in a cone-like shape in which the diameter enlarges upward. The supporting structure comprises a shell-like support member, a first mesh layer comprising thick mesh elements, and a second mesh layer having a mesh size which does not allow catalyst particles to pass through. The first mesh layer overlays the support member, and the second mesh layer overlays the first mesh layer. The shell-like support member includes a circular bottom plate extending perpendicular to the center line of the reactor, and a side wall having a truncated cone shape which extends upward from the edge of the bottom plate. The bottom plate and the side wall are primarily made of perforated plates through which the fluid passes. A plurality of cylindrical flow guides of different diameters are provided underneath the shell-like support member.
There is a need for a reactor with a catalyst support which can be easily and quickly serviced and replaced to lower the down-time of the reactor and thus lower the service costs.